This invention relates to a method of preparing a kneaded composition by using a powder of a hydraulic substance as cement.
Although any hydraulic substance for example, plaster and various kinds of cement, can be used, since Portland cement is most widely used in various civil works and in constructing buildings as precast products or blasing or pouring in the form of a paste, mortar or green concrete, in the following description and the appended claims the term cement is used to include any hydraulic substance that can be used for working out the method of this invention.
To prepare a cement paste, mortar or green concrete, a suitable quantity of water is added to a powder of cement and the mixture is then kneaded. Usually at least 90% (in the following description, in most cases, percentage is weight percent) of the total quantity of water is first added to cement and the remaining quantity of the water is added at the final stage of kneading. With such a prior art method, however, a substantial quantity of water bleeds out when the kneaded compound is cast or shaped into a desired product. Moreover, the mechanical strength of the product is not always high and uniform. In the past, it has been considered that such defects were inevitable for cement or concrete products, and a substantial bleeding time was used to finish the surface of products or to determine the percentage of ingredients or to design the concrete products and use mortar or concrete by taking into consideration such bleeding time. Although many attempts have been made, it has been impossible to completely eliminate the defects described above.